The demand for substrate materials for use in printed circuits has increased drastically with the development of printed circuitry in the electronics industry. As resins for such substrates phenolic resins, epoxy resins and other thermosetting resins have been used commercially because of their reasonable costs and good performance. However, the use of phenolic resins suffers the defect that, due to their poor adhesiveness to copper foils, the copper foils must be precoated with an adhesive. As a consequence, at present, epoxy resins are used in large quantities for this purpose. These epoxy resins, however, are not very satisfactory in their electrical properties. On the other hand, the 1,2 -polybutadienes show excellent electrical properties. The latter resins, however, occur in the form of viscous liquids having low cure rates and do not show satisfactory adhesion to copper foils, which fact renders them difficult to use in printed circuit applications. Due to the large number of double bonds in their structure, 1,2-polybutadienes may be polymerized with a radical polymerization catalyst to produce thermosetting resins. In fact, however, the 1,2-polybutadienes exhibit very low curing rates, so that attempts to cure them by the use of a peroxide as an oxidizing agent together with a metal naphthenate as a cocatalyst result in an insufficiently cured product. Attempts to perfect curation require treatment at high temperatures over a long period of time, and are therefore unsuitable from the standpoint of commercial use.